Tattoos have gained popularity over the years studies have indicated that 20-25% of populations in several countries have tattoos. The rate is even higher among younger generations. As more people get tattoos, questions about tattoo ink safety are emerging. Epidemiological research on the carcinogenicity of these inks in relation to skin, internal organs, and immunity remains a huge gap.
Black ink poses a concern to health because it is made up of carbon black which the International Agency for Research on Cancer (IARC) has classified as probably carcinogenic to humans. Azo compound-based red inks can further release carcinogenic amines upon exposure to sunlight or laser removal procedures. These colors can also result in allergic reactions to the skin and thus increase health risks.
The Danish Twin Tattoo Cohort (DTTC) in 2021, provided valuable insights into the possible connection between tattoo ink exposure and risks of cancer. The study investigated these risks using case-control research and larger cohort studies. From January to July 2021, the DTTC surveyed Danish twins to collect information on exposure to tattoo ink. The cohort ranged from 1960 to 1996 birth years and cases were classified according to the Nordic Cancer Registration System.
The case-cotwin study recruited participants who were born between 1960 and 1996. As of January 1, 2017, all the participants had attained the age of 20 years. Eligibility to join the study was at least one of the twins must have had a diagnosis of non-Hodgkin lymphoma, Hodgkin lymphoma, skin cancer except for basal cell carcinoma, or bladder/urinary tract cancer after age 20. At least one twin had to be alive and residing in Denmark. Of 568 eligible twins, 504 met both conditions, and 316 (56%) completed the survey.
A larger cohort study was conducted with 2,459 twin pairs who were randomly selected from the Danish Twin Registry (DTR). An invitation was sent to 4,532 twins; 2,367 (52%) responded with 673 pairs consisting of both twins. The study focused on three outcomes basal cell carcinoma, skin cancer, and lymphoma.
The findings revealed that extensive tattoo exposure was associated with an increased risk of lymphoma, with a hazard ratio (HR) of 2.73 (95% confidence interval (CI): 1.33–5.60), compared to no tattoos. For skin cancer, the HR was 1.62 (95% CI: 1.08–2.41). Larger tattoos further elevated the risk, with an HR of 2.37 (95% CI: 1.11–5.06), while no significant effect was observed for red ink exposure (HR: 1.44, 95% CI: 0.85–2.45). Smoking did not influence these findings.
A matched investigation of 14 twin pairs found a discordant relationship between tattoo exposure and skin cancer, with an HR of 3.91 (95% CI: 1.42–10.78) for skin cancer and 2.83 (95% CI: 1.30–6.16) for basal cell carcinoma. Combined, these cancers resulted in an HR of 3.28 (95% CI: 1.76–6.09). Adjusting for smoking, the HR for basal cell carcinoma was 3.52 (95% CI: 1.63–7.61). However, no matched case-cotwin analysis was available for lymphoma.
This study’s findings indicated that individuals with tattoos could be at an increased risk of developing lymphoma and skin cancer. This is particularly concerning given the rising prevalence of tattoos, especially among younger generations. Although tattoos are a widely accepted form of self-expression, this research highlights potential health risks associated with tattoo ink. Further investigation is essential to cover the mechanisms behind tattoo ink-induced cancer development and establish effective public health strategies for prevention.
References: Clemmensen SB, Mengel-From J, Kaprio J, et al. Tattoo ink exposure is associated with lymphoma and skin cancers – a Danish study of twins. BMC Public Health. 2025;25:170. doi:10.1186/s12889-025-21413-3
